There are some Charismatic/Pentecostal groups who talk about praying in a "warring tongue." The idea that they have is that you are to rebuke the devil, bind spirits and etc. by agressively speaking in tongues.
I've heard others who tried to disuade people from doing this based upon
2 Peter 2:11 and
Jude 1:9.
Without knowing the context and also all of the things that the pastor/evangelist may be dealing with locally it's only speculation as to what's going on.
Personally I don't think we need to bring railing accusations or to shout ourselves hoarse in battling the adversary. The desire to do so may be symptomatic of other issues or may be caused by people just copying the behavior of others that they see.